• Rehabilitation will be influenced by the farm contour, availability of suitable machinery, finance and human resources.
  • Ash does not dissolve or percolate into the soil profile, therefore tillage with high inputs of fertilizer is required (providing a medium for establishing ryegrass/white clover pastures).
  • Ashfalls of 50 mm will have serious financial implications in the year of the ashfall and also the following season.

Land Able to be Cultivated

  • Ploughing as deep as 20 cm (8 in) gives best results, as the ash layer is mixed with underlying soil. Incorporation of ash will still result in changes to the soil characteristics, such as greater soil moisture, lower fertility and permeability. Large scale cultivation will be expensive.
  • Costs include re-grassing, fertilizer and high machinery maintenance costs due to the abrasive nature of the ash increasing wear and tear.
  • Rehabilitation of land affected by ash is similar to development of sand country where the initial requirement is establishment of any species tolerant of the conditions to stabilize the ash and build up fertility.
  • Re-establishment of pastoral species, dependent on the nature of the ash. With very acidic ash, liming could be required, along with high fertilizer inputs to create a soil medium, conducive to pastoral growth.
  • Initially, acid tolerant species and species more tolerant of severe conditions may need to be planted. For example, Marram grass, lupins, Yorkshire Fog and Lotus.
  • These species tend to be lower yielding than the existing ryegrass and clover pastures. Once soil fertility and organic matter levels increase, more productive species may be established.

Land Not Able to be Cultivated

  • Rehabilitation will be a slow and costly process.
  • Oversowing of low fertility species with fertilizer inputs may be required.
  • It may be un-economic for land to resume pastoral use; other land use may be appropriate.
  • Rehabilitation will be dependent on the financial resources of the farmer, which may be extremely limited after the financial toll of the eruption.


  • May require de-stocking of the land for at least 6 months.
  • Rehabilitation will require re-stocking, but may not be physically possible where the eruption devastates a large area.
  • Slaughtering of stock may be the only option, which will result in a loss of valuable stock of high genetic merit.
  • Until the ash consolidates, quality water for stock will be scarce.
  • Extra expense will be incurred in maintaining water pumps (affected by the abrasive nature of the ash).
  • The physical removal of the ash from buildings, yards, roadways will be required. Methodology available in the Clean-up and Disposal section.